NTP Servers in France: Complete Guide & Comparison
An up-to-date NTP France directory
The French NTP landscape has historically relied on lists established by Renater and the CRU (Comite Reseau des Universites). These references played a founding role, but they have not been updated for years — the last CRU version dates back to 2007. Some listed servers still run on hardware from the 1990s, and some are officially decommissioned yet still referenced.
Nobody maintains an up-to-date overview. This page fills that gap: NTP pool France, NTS servers, institutional stratum 1, academic and independent stratum 2, hyperscalers. With ready-to-copy configuration examples.
NTP Pool France (fr.pool.ntp.org)
For the majority of use cases, the NTP pool France is the default choice. It is a geolocation-based DNS round-robin system that automatically redirects clients to nearby and reliable servers. Approximately 200 IPv4 servers participate in the France zone.
| Address | Description |
|---|---|
fr.pool.ntp.org |
France zone, automatic assignment |
0.fr.pool.ntp.org to 3.fr.pool.ntp.org |
Sub-zones (useful for configuring 4 distinct sources) |
Advantages:
- Decentralized, community-driven, natively supported by all operating systems
- Reliable — the scoring system automatically removes failing servers
- RDEM Systems is an active contributing member of the pool with >10 Stratum 2 servers
Limitations:
- No NTS — the DNS round-robin mechanism is incompatible with NTS, because each server requires its own TLS certificate. You cannot authenticate a server whose address you do not know in advance.
- No choice of specific server (the pool decides)
- Variable quality depending on contributors
An ICANN-funded project (2025-2027) is working on a solution to make NTS compatible with the pooling mechanism. Until then, NTS requires configuring individual NTS servers alongside the pool.
NTS in France — the current state
NTS (Network Time Security) authenticates and encrypts NTP exchanges, preventing interception and spoofing attacks. It is the future of the protocol, but its deployment remains marginal: approximately 60 to 70 public NTS servers worldwide, of which 45 to 50 are in Europe.
In France, the available NTS options can be counted on one hand:
| Server | Operator | Location | Stratum | Details |
|---|---|---|---|---|
ntp1 to ntp11.rdem-systems.com |
RDEM Systems | Paris area | 2 | NTS >10 servers, primarily AS206014, private NTS pool |
paris.time.system76.com |
System76 (USA) | Paris | 2 | NTS Dedicated Parisian node. NTS by default on Pop!_OS since 22.04 |
ntp.viarouge.net |
Hubert Viarouge | Nancy | 2 | NTS VPS Debian, chrony 4.3, NTS on port 4460/TCP TLS 1.3. FR pool member |
time.cloudflare.com |
Cloudflare | Anycast (Paris/Marseille nodes) | 2 | NTS US hyperscaler, not French but low latency from France |
Observation: NTS is 100x rarer than standard NTP
The FR pool has ~200 IPv4 servers. NTS servers reachable from France can be counted on two hands. RDEM Systems is the only independent French operator offering an NTS pool of approximately 10 servers — an order of magnitude above what else exists in France.
European context: NTS reference operators
To put the French offering in perspective, here are the main NTS operators in Europe:
| Operator | Country | NTS servers | Type |
|---|---|---|---|
| Netnod | Sweden | 12+ (anycast + localized: Stockholm, Gothenburg, Malmo, Lulea, Sundsvall) | NTS pioneers, reference infrastructure |
| PTB | Germany | 4 | National metrology institute |
| SIDN Labs | Netherlands | Yes | .nl registry |
| Trifence AG | Switzerland | Yes (ntp.zeitgitter.net, ntp.trifence.ch) | Independent |
| RDEM Systems | France | >10 | Independent, NTP pool contributor |
French Stratum 1 servers (primary sources)
| Server | Operator | Location | Reference | Access | Status |
|---|---|---|---|---|---|
ntp-p1.obspm.fr |
LNE-SYRTE, Observatoire de Paris | Paris | Cesium / H Maser, UTC(OP) | Open (notify first) | Active — national reference |
saturne.obs-besancon.fr |
LNE-LTFB, Obs. Besancon | Besancon | HP5071A atomic clock, traced to UTC(OP) | Stratum 2 only (notify first) | Active |
ntp.cines.fr |
CINES | Montpellier | Symmetricom NTS 200 | Restricted to education/research | Active |
ntp1.jussieu.fr |
Universites Paris VI/VII | Paris | GPS Lantronix NTP-E1 | Open (notify first) | Responds as S2 — historically listed as S1, but responds as Stratum 2 (March 2026) |
ntp.deuza.net |
Gandi/Parix | Paris | FreeBSD | Open | Active — announces Stratum 1 (March 2026) |
ntp.genoscope.cns.fr |
Genoscope | Evry | Truetime NTS200 | Stratum 2 (notify first) | Active (no guarantee, may be discontinued) |
time.kuro-home.net |
Independent | Besancon | GPS, LeonNTP | Open | Active |
chronos.cru.fr |
CRU / Univ. Rennes 1 | Rennes | GPS (degraded) | Conditional | DNS KO — domain no longer resolves (March 2026). Former S1 downgraded to S2 since 2015 |
canon.inria.fr |
INRIA | Rocquencourt | GPS Datum | Open (notify first) | DNS KO — domain no longer resolves (March 2026) |
ntp-sop.inria.fr |
INRIA | Sophia Antipolis | GPS | Stratum 2 (notify first) | DNS KO — domain no longer resolves (March 2026) |
ntp.pasteur.fr |
Institut Pasteur | Paris | — | — | Stopped June 2014 |
The source lists (Renater, CRU) have not been updated since 2007-2015. Several servers listed as Stratum 1 may have been decommissioned, degraded, or replaced without the references being corrected. The statuses above reflect our verification of March 10, 2026 via
ntpdate -q.
A server responding with
REFUSED is not necessarily out of service. It may indicate
IP-based filtering, restricted access to the academic network (Renater), or a whitelist policy.
The server is reachable but declines NTP requests from our test point.
French Stratum 2 servers
Independent and community-operated
| Server | Operator | Location | NTS | Notes |
|---|---|---|---|---|
ntp1 to ntp11.rdem-systems.com |
RDEM Systems (AS206014) | Paris area | NTS | >10 servers, IPv4+IPv6, primarily Equinix, global NTP pool. Since 2005 |
ntp.crashdump.fr |
Crashdump | Rennes | No | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.midway.ovh |
OVH | Gravelines | No | REFUSED — responds but refuses NTP queries (March 2026) |
time.resolvlab.com |
ResoLv SARL | Clermont-Ferrand | No | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.ilianum.com |
SKV Consulting | Pontoise | No | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.accelance.net |
Accelance SA | Lyon | No | — |
Academic and research network (Renater)
| Server | Operator | Location | Notes |
|---|---|---|---|
ntp.obspm.fr |
Observatoire de Paris | Paris | Stratum 2 of LNE-SYRTE |
ntp.univ-rennes2.fr |
Univ. Rennes 2 | Rennes | DNS round-robin (ntp1 + ntp2) |
ntp.lothaire.net |
Univ. Lorraine | Nancy | IPv4 + IPv6, alias (IP may change) |
ntp.laas.fr |
LAAS/CNRS | Toulouse | DNS alias |
ntp.u-psud.fr |
Univ. Paris-Sud | Orsay | Alias (IP may change) |
ntp.unicaen.fr |
Univ. Caen | Caen | Alias (IP may change) |
ntp.unice.fr |
Univ. Nice | Nice | CentOS |
ntp.ensma.fr |
ENSMA | Poitiers | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.polytechnique.fr |
Ecole Polytechnique | Saclay | Orolia/Safran hardware, redundant stratum 2. On request |
ntp.sophia.cnrs.fr |
DR20 CNRS | Sophia Antipolis | DNS alias |
ntp.univ-lyon1.fr |
CISM | Lyon | — |
ntp.univ-angers.fr |
Univ. Angers | Angers | — |
chronos.espci.fr |
ESPCI | Paris | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.via.ecp.fr |
Ecole Centrale Paris | Paris | REFUSED — responds but refuses NTP queries (March 2026) |
ntp.univ-reims.fr |
Univ. Reims | Reims | Active (March 2026) |
ntp.emi.u-bordeaux.fr |
Univ. Bordeaux | Bordeaux | Active (March 2026) |
ntp2.emn.fr |
Ecole des Mines de Nantes | Nantes | Active (March 2026) |
ntp.relier.fr |
Relier | France | Active (March 2026) |
delphi.phys.univ-tours.fr |
Univ. Tours | Tours | Active (March 2026) |
ntp.uvsq.fr |
Univ. Versailles | Versailles | Active — responds as Stratum 3 (March 2026) |
These servers are the historical pillars of NTP in France. Many still run on legacy hardware (NTP v3, Sun, Cisco, HP-UX, DEC Alpha) and do not support NTS. They are nevertheless stable and have been running for 20 years or more — a testament to their reliability. Their main weakness is the lack of active maintenance of reference lists.
Hyperscalers (anycast with nodes in France)
| Server | Operator | NTS | Specifics |
|---|---|---|---|
time.cloudflare.com |
Cloudflare | NTS | Anycast Paris/Marseille, very fast |
time.google.com |
No | Leap smearing: spreads leap seconds over 24h instead of an instant step. Can cause offsets with other sources during leap second events | |
time.facebook.com |
Meta | No | Stratum 1, very accurate. Leap smearing |
Google and Meta spread leap seconds over 24 hours instead of inserting them instantly. During this window, their servers report a slightly different time than traditional NTP servers. Never mix sources with and without leap smearing in the same configuration. Learn more about leap seconds.
French NTP appliance manufacturers
These companies do not offer public NTP services, but they are part of the French time ecosystem. They design and manufacture NTP/PTP appliances for enterprise, defense, and industrial use.
- Bodet Time (Trementines, Maine-et-Loire) — since 1868. NETSILON range: GPS/GLONASS/Galileo/BeiDou, NTP/PTP, designed and manufactured in France. Multi-source (satellite, ALS162/DCF77 radio, network).
- Gorgy Timing (Buzancais, Indre) — since 1979. LEDI range. Clients in defense, aerospace, industry, and transportation.
RDEM Systems performs 1-day NTP audits: source verification, redundancy, MiFID II / PCI-DSS compliance, and remediation plan. Discover our services →
Summary and positioning
French NTP infrastructure has historically relied on the academic world: universities, CNRS, grandes ecoles, research institutes. These servers are stable — some have been running for over 20 years — but aging: often NTP v3, hardware sometimes 20+ years old, no NTS support, unmaintained reference lists.
Key findings:
- The fr.pool.ntp.org pool (~200 IPv4 servers) remains the pragmatic default choice
- NTS is virtually absent in France: only 3 operators — RDEM Systems (>10 NTS servers), System76 (1 Parisian node), Viarouge (1 server in Nancy)
- Hyperscalers (Cloudflare, Google, Meta) offer massive but centralized, non-sovereign reliability
- French NTP hardware is well represented (Bodet, Gorgy) but it is an appliance market, not a public service
Where does RDEM Systems fit?
RDEM Systems positions itself as the leading independent French NTS operator — a modern complement to the ecosystem, not a replacement. An active member of pool.ntp.org since 2005, with an infrastructure documented and proven over 20 years.
- >10 public NTS servers (ntp1 to ntp11.rdem-systems.com)
- 1 Stratum 1 GNSS server (GPS + Galileo) with PPS — technical details
- Own network AS206014, peering at Parisian IXPs, Equinix hosting
- Dual-stack IPv4/IPv6, 8 different TLDs, 24/7 monitoring
- Reliability score available on ntppool.org
Recommended configuration
Standard usage: Chrony + FR pool
# /etc/chrony/chrony.conf
# NTP Pool France (primary source)
pool fr.pool.ntp.org iburst maxsources 4
# Complementary servers (French operator, Stratum 2)
server ntp1.rdem-systems.com iburst
server ntp2.rdem-systems.com iburst
# Fast sync on startup
makestep 1 3
rtcsyncSecure usage: Chrony + NTS
# /etc/chrony/chrony.conf - with NTS
# FR pool as base (NTS not possible on the pool)
pool fr.pool.ntp.org iburst maxsources 3
# French NTS servers (authentication + encryption)
server ntp1.rdem-systems.com iburst nts
server ntp2.rdem-systems.com iburst nts
server ntp3.rdem-systems.com iburst nts
makestep 1 3
rtcsyncHigh precision: Chrony + NTS + institutional Stratum 1
# /etc/chrony/chrony.conf - maximum precision
# Institutional Stratum 1 (notify operator before use)
server ntp-p1.obspm.fr iburst
# French NTS servers
server ntp1.rdem-systems.com iburst nts
server ntp2.rdem-systems.com iburst nts
# FR pool as complement
pool fr.pool.ntp.org iburst maxsources 2
makestep 1 3
rtcsyncWindows (w32tm)
REM French NTP servers (FR pool + RDEM Systems)
w32tm /config /manualpeerlist:"0.fr.pool.ntp.org 1.fr.pool.ntp.org ntp1.rdem-systems.com ntp2.rdem-systems.com" /syncfromflags:manual /reliable:yes /update
net stop w32time && net start w32time
w32tm /resyncAlways configure at least 3 NTP sources. The selection algorithm needs multiple sources to detect anomalies (falsetickers). Prefer geographically nearby sources to minimize latency. And never mix sources with and without leap smearing.
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